Reducing fuel consumption in Portuguese coastal trawlers by using trawls with higher tenacity fibres

摘要

Trawling is an intensive fuel consumption fishing technique and therefore vessel's profits are highly dependent on oil price fluctuation. The percentage of fuel in total costs, for the Portuguese coastal trawlers, can be as high as 40%. Gear alterations may contribute to a decrease in drag during trawling and thus fuel consumption. A standard trawl built in braided polyethylene was replaced by a modified one made of high tenacity fibres, with a small increase in mesh sizes at the front panels, resulting in 30% decrease of the twine area. Significant improvements in fuel consumption per unit of mouth area were attained, ranging from 13 to 21% as the towing speed increased from 3.6 to 4.4 knots. The qualitative assessment by the vessel's skipper was rather positive, the fishing performance was maintained while the new trawl required less effort from the engine, at the usual trawling speed.